1. Field of the Invention
The present invention relates to a copying apparatus in which scanning is carried out by allowing the document table, carrying the originals to be copied, to move against the body.
2. Description of the Prior Art
In a copying apparatus whose document table moves, the optical system is fixed to the body and the original to be copied is scanned by activating the document table relative to the body.
When a heavy and thick book is copied, the book is often held down by the operator, applying an excessively great load to the copying apparatus during moving of a document table.
For example, in a copying apparatus operating at predetermined speeds both during scanning (forward) and returning (backward), an excessively great load prevents the machine from attaining the specified speed level or causes an irregular speed range. In general, to improve copying efficiency, the returning speed is set faster than the speed for scanning, and therefore the foregoing load will create serious problems especially during a returning mode of operation. In addition, in such event the driving noise (noise generated by the motor) becomes unstable, causing the user to feel uneasy.
To cope with such circumstances, inventions such as Japanese Patent Application Laid-Open No. 61-63831 (1987) have been proposed.
This invention is directed to a copying apparatus that moves the scanning optical system relative to the copier body. The apparatus detects the moving speed of the scanning optical system, and if the result proves that the speed is slower than a predetermined value, the apparatus determines an abnormal state and stops the scanning optical system. Now, the copying apparatus that moves a document table has greater possibilities to produce improper movement of the document table due to the weight of originals as described before. However, because in such event the trouble is not caused by irregularity of the driving system, stopping the document table on all such occasions reduces greatly the operation efficiency of the copying apparatus.